package com.samp.base.jce.type03;

import java.io.ByteArrayOutputStream;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;
import java.util.HashMap;
import java.util.Map;

import javax.crypto.Cipher;

/**
 * RSA算法是现今使用最广泛的公钥密码算法,也是非对称密码算法。
 * RSA算法较慢，对加密数据长度有限制，一般用于密码等较短信息的加解密，较多的信息可以考虑AES对称加密。
 * 参考：https://blog.csdn.net/dbs1215/article/details/48953589
 * https://www.cnblogs.com/nanyangke-cjz/p/5898361.html
 */
public class RSAUtils {


    /**
     * 加密算法RSA
     */
    public static final String KEY_ALGORITHM = "RSA";

/** */
    /**
     * 签名算法
     */
    public static final String SIGNATURE_ALGORITHM = "MD5withRSA";

/** */
    /**
     * 获取公钥的key
     */
    private static final String PUBLIC_KEY = "RSAPublicKey";

/** */
    /**
     * 获取私钥的key
     */
    private static final String PRIVATE_KEY = "RSAPrivateKey";

/** */
    /**
     * RSA最大加密明文大小
     */
    private static final int MAX_ENCRYPT_BLOCK = 117;

/** */
    /**
     * RSA最大解密密文大小
     */
    private static final int MAX_DECRYPT_BLOCK = 128;

/** */
    /**
     * <p>
     * 生成密钥对(公钥和私钥)
     * </p>
     *
     * @return
     * @throws Exception
     */
    public static Map<String, Object> genKeyPair() throws Exception {
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        Map<String, Object> keyMap = new HashMap<String, Object>(2);
        keyMap.put(PUBLIC_KEY, publicKey);
        keyMap.put(PRIVATE_KEY, privateKey);
        return keyMap;
    }

/** */
    /**
     * <p>
     * 用私钥对信息生成数字签名
     * </p>
     *
     * @param data
     *            已加密数据
     * @param privateKey
     *            私钥(BASE64编码)
     *
     * @return
     * @throws Exception
     */
    public static String sign(byte[] data, String privateKey) throws Exception {
        byte[] keyBytes = Base64.getDecoder().decode(privateKey);
        Base64.getDecoder().decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(privateK);
        signature.update(data);
        return Base64.getEncoder().encodeToString(signature.sign());
    }

/** */
    /**
     * <p>
     * 校验数字签名
     * </p>
     *
     * @param data
     *            已加密数据
     * @param publicKey
     *            公钥(BASE64编码)
     * @param sign
     *            数字签名
     *
     * @return
     * @throws Exception
     *
     */
    public static boolean verify(byte[] data, String publicKey, String sign) throws Exception {
        byte[] keyBytes = Base64.getDecoder().decode(publicKey);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PublicKey publicK = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(publicK);
        signature.update(data);
        return signature.verify(Base64.getDecoder().decode(sign));
    }

/** */
    /**
     * <P>
     * 私钥解密
     * </p>
     *
     * @param encryptedData
     *            已加密数据
     * @param privateKey
     *            私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(byte[] encryptedData, String privateKey) throws Exception {
        byte[] keyBytes = Base64.getDecoder().decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateK);
        int inputLen = encryptedData.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }

/** */
    /**
     * <p>
     * 公钥解密
     * </p>
     *
     * @param encryptedData
     *            已加密数据
     * @param publicKey
     *            公钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey) throws Exception {
        byte[] keyBytes = Base64.getDecoder().decode(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, publicK);
        int inputLen = encryptedData.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }

/** */
    /**
     * <p>
     * 公钥加密
     * </p>
     *
     * @param data
     *            源数据
     * @param publicKey
     *            公钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(byte[] data, String publicKey) throws Exception {
        byte[] keyBytes = Base64.getDecoder().decode(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, publicK);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }

/** */
    /**
     * <p>
     * 私钥加密
     * </p>
     *
     * @param data
     *            源数据
     * @param privateKey
     *            私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data, String privateKey) throws Exception {
        byte[] keyBytes = Base64.getDecoder().decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateK);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }

/** */
    /**
     * <p>
     * 获取私钥
     * </p>
     *
     * @param keyMap
     *            密钥对
     * @return
     * @throws Exception
     */
    public static String getPrivateKey(Map<String, Object> keyMap) throws Exception {
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return Base64.getEncoder().encodeToString(key.getEncoded());
    }

/** */
    /**
     * <p>
     * 获取公钥
     * </p>
     *
     * @param keyMap
     *            密钥对
     * @return
     * @throws Exception
     */
    public static String getPublicKey(Map<String, Object> keyMap) throws Exception {
        Key key = (Key) keyMap.get(PUBLIC_KEY);
        return Base64.getEncoder().encodeToString(key.getEncoded());
    }

    /**
     * java端公钥加密
     */
    public static String encryptedData(String data, String PUBLICKEY) {
        try {
            data = Base64.getEncoder().encodeToString(encryptByPublicKey(data.getBytes(), PUBLICKEY));;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return data;
    }

    /**
     * java端私钥解密
     */
    public static String decryptData(String data, String PRIVATEKEY) {
        String temp = "";
        try {
            byte[] rs = Base64.getDecoder().decode(data);
            temp = new String(RSAUtils.decryptByPrivateKey(rs, PRIVATEKEY),"UTF-8"); //以utf-8的方式生成字符串

        } catch (Exception e) {
            e.printStackTrace();
        }
        return temp;
    }

    public static void main(String[] args) {
        try {
            Map<String, Object> keyMap = genKeyPair();
            String privateKey = getPrivateKey(keyMap);
            String publicKey = getPublicKey(keyMap);
            System.out.println("privateKey:"+privateKey);
            System.out.println("publicKey:"+publicKey);
            privateKey = "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";
            publicKey = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCByVQAn66TIpGJ671iH9VUgjPi7co7BqSxA5HoJE1BBkGuEKopt9hgK4My9uI5ygFfb00UH6+fhdWMxrrVdSY58TCRrqzKdIZJ3cUQnkvO7KpYFvC7x+ia8+JmZgPHDHK7F7XOLfXfOtlsf4I6IwnGZu+lqpdq/tdKfz4yJn2m9QIDAQAB";
            String msg = "今天成都天气不是很好。、、\\/ab,cd";
            String encryptMsg = encryptedData(msg, publicKey);
            System.out.println("encryptMsg:"+encryptMsg);
            encryptMsg = "Kw/81IZUfm8z7emkFTHsANWKkR1F8KCOH0RAZ+QjuzCqn4CNIzjYk1tOj3QxvWqR7FKSmlP56jsr7X6uEbzqA0tVo2vD062yibh+b9siuRVARsYXhh6PPuYEvtMSju/PPkaDaFRZM77jim+J8Z1H78+mUCX8e20/DqM6uTFmnV0=";
            String decryptMsg = decryptData(encryptMsg,privateKey);
            System.out.println("decryptMsg:"+decryptMsg);
        }catch (Exception e){
            e.printStackTrace();
        }

    }
}
